AB0747 NON-INFECTIOUS AORTITIS: CLINICAL AND HISTOLOGICAL CORRELATION
Authors: C. Sieiro Santos, P. Moya, L. López Vilaró, C. Moriano, I. Castellví, A. J. Barros-Membrilla, B. Magallares, H. Park, H. Codes, A. Laiz, S. P. Fernandez-Sanchez, E. Diez Alvarez, H. Corominas
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Isolated aortitis is considered a single organ vasculitis in the latest 2012 International Chapel Hill Consensus Conference revision. Despite being an increasingly diagnosed condition thanks to imaging tests, given the difficulty in completing the histological study, it is frequently unknown whether it is an isolated entity or a clinical manifestation of other vasculitis or rheumatologic entities. <h3>Objectives</h3> To describe the histological findings in samples of inflammatory aortic aneurysms and correlate them with their clinical presentation. <h3>Methods</h3> A descriptive cross-sectional study was performed. Aortic biopsies from elective aortic aneurysm surgery performed at a university hospital from 2019 to 2021 were reviewed. The samples with a non-infectious inflammatory pattern were selected. Cases of aortitis secondary to infection and/or atherosclerosis were excluded. The samples were reviewed again by a pathologist specialized in vascular wall disease and classified according to the 2015 consensus on surgical pathology of the aorta of the Society for Cardiovascular Pathology and the European Association of Cardiovascular Diseases in granulomatous pattern, lymphoplasmacytic pattern and mixed inflammatory pattern. Likewise, the pathologist, taking into account the previous classification and the findings, assigned a diagnostic orientation, only taking into account the histological findings. Demographic, clinical, laboratory data and the diagnostic orientation of the rheumatologist were collected. <h3>Results</h3> Of the 116 aortic tissue samples reviewed, inflammatory findings were observed in 10 (9%) of the biopsies. Characteristics of the patients whose biopsies were included are shown in Table 1. 80% of the samples came from the proximal aorta, 10% from the aortic arch, and the remaining 10% from the abdominal aorta. The mean diameter of the aneurysm was 61.7 ± 21 millimeters. The rheumatologist's clinical diagnosis for the patients included was: 1 patient with Giant Cell Arteritis, 1 patient with Takayasu's disease, 1 patient with Behçet's disease, 1 patient with HLA-B27-associated spondyloarthropathy, and 6 patients with idiopathic aortitis. Histologically, 8 patients presented a lymphoplasmacytic pattern, 1 patient a granulomatous pattern, and 1 patient a mixed inflammatory pattern. The diagnostic orientation of the pathologist coincided with the clinician in 9/10 of the cases. The most frequent final diagnosis was nonspecific isolated aortitis (7/10), followed by Giant Cell Arteritis (1/10), Takayasu's arteritis (1/10) and Behçet's disease (1/10). There is a concordance between the histological pattern and the diagnostic orientation of the pathologist with the diagnostic orientation of the clinician in 9 of the 10 cases. <h3>Conclusion</h3> There is a high concordance between histopathologic and clinical diagnosis in the patients included in this study. Despite this, there is a high prevalence of non-specific aortitis, yet to be identified. Non-granulomatous lymphoplasmacytic pattern is the most reported in our series of cases. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.